Vibration type angular rate sensor

Abstract

This vibration-type angular velocity sensor (100) is configured so as to be able to: switch electrodes (50) that induce a primary vibration in a vibrator (1); and switch electrodes (50) that detect a secondary vibration of the vibrator (1). An offset value after switching and an offset value prior to switching are symmetrical relative to a prescribed reference value.

Description

[Technical field]

[0001] The present invention relates to a vibration type angular velocity sensor, and more particularly to a vibration type angular velocity sensor having a primary side control circuit that induces a primary vibration in a vibrator and a secondary side control circuit that detects and outputs a secondary vibration generated in the vibrator due to an angular velocity applied to the vibrator. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a vibration type angular velocity sensor is known. Such a vibration type angular velocity sensor is disclosed in, for example, JP 2009-115559 A and Japanese Patent No. 6463335.

[0003] In JP 2009-115559 A, a ring-shaped element part and a plurality of electrodes are arranged radially outside and circumferentially of the ring-shaped element part. The plurality of electrodes include a primary electrode and a secondary electrode. An AC power source is connected to one of the primary electrode and the secondary electrode to generate a primary vibration in the ring-shaped element part. A detection means is connected to the other of the primary electrode and the secondary electrode to detect the magnitude of an electric signal generated in the ring-shaped element part. When a rotational motion occurs around the normal direction of the element part while the primary vibration is generated in the ring-shaped element part, a secondary vibration corresponding to the angular velocity of the rotational motion is generated in the element part. The detection means connected to the other of the primary electrode and the secondary electrode detects the magnitude of the electric signal generated in the other of the primary electrode and the secondary electrode due to the secondary vibration. An AC voltage for canceling the secondary vibration is applied to one of the primary electrode and the secondary electrode based on the magnitude of the detected electric signal. The magnitude of the angular velocity is calculated based on the magnitude of the AC voltage for canceling the secondary vibration.

[0004] Furthermore, in a conventional vibration type angular velocity sensor such as that described in JP 2009-115559 A, the angular velocity detected by the vibration type angular velocity sensor contains a bias component (an error from the zero point output from the sensor even when no angular velocity is applied). The bias component is generated due to the asymmetry of the gyro element included in the vibration type angular velocity sensor. Therefore, a conventional vibration type angular velocity sensor such as that described in JP 2009-115559 A is configured to switch between an electrode (one of the primary electrode and the secondary electrode) to which an AC power supply is connected and an electrode (the other of the primary electrode and the secondary electrode) to which a detection means is connected. Then, the bias component is cancelled by calculating the difference between the outputs of the vibration type angular velocity sensor before and after the switching.

[0005] In a vibration type angular velocity sensor that cancels bias components by switching between an electrode connected to an AC power source and an electrode connected to a detection means as described in JP 2009-115559 A, a bias component may remain without being canceled. In this case, the remaining bias component fluctuates depending on the temperature of the surrounding environment.

[0006] Japanese Patent No. 6463335 discloses a vibration type angular velocity sensor including a primary control circuit that induces a primary vibration in a vibrator and a secondary control circuit that detects and outputs a secondary vibration generated in the vibrator due to an angular velocity applied to the vibrator. In this vibration type angular velocity sensor, both the primary control circuit and the secondary control circuit are configured with a closed control loop. In addition, a first offset value based on the output of the primary control circuit that is inversely proportional to the temperature change of the gain of the vibrator and a second offset value based on a constant signal that is independent of temperature are added to the closed control loop of the secondary control circuit. This reduces an error caused by crosstalk from the primary control circuit to the secondary control circuit (an error inversely proportional to the first and second powers of the gain of the vibrator). The first and second offset values ​​are adjusted to reduce an error caused by crosstalk from the primary control circuit to the secondary control circuit. This corrects the sensor output from the secondary control circuit. As a result, it becomes possible to reduce the temperature fluctuation of the output from the vibration type angular velocity sensor (the change in the output value due to the surrounding temperature).

[0007] Furthermore, in a vibration-type angular velocity sensor such as that described in JP 2009-115559 A, which switches between an electrode connected to an AC power supply and an electrode connected to a detection means to cancel the bias component, by applying the configuration of Japanese Patent No. 6463335 before and after the switching, it is possible to reduce the temperature fluctuation of the remaining bias component. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2009-115559 A [Patent Document 2] Patent No. 6463335 Summary of the Invention [Problem to be solved by the invention]

[0009] However, as described in JP 2009-115559 A, in order to cancel the bias component by switching between the electrode connected to the AC power supply and the electrode connected to the detection means, the symmetry of the control of the vibration type angular velocity sensor before and after the switching is important. Here, if the configuration of JP 6463335 A is applied before and after the switching and the first and second offset values ​​are set separately before and after the switching, the first and second offset values ​​before and after the switching are generally not symmetrical. Therefore, if the first and second offset values ​​are set asymmetrically before and after the switching, the symmetry of the control of the vibration type angular velocity sensor is lost, which causes a problem that the temperature fluctuation component of the bias that is not canceled and remains may become large.

[0010] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a vibration type angular velocity sensor that can suppress the increase in the temperature fluctuation component of the bias that remains without being canceled. [Means for solving the problem]

[0011] In order to achieve the above-mentioned object, a vibration type angular velocity sensor according to a first aspect of the present invention comprises a vibrator, a primary side control circuit having a closed control loop, the output of which induces a primary vibration in the vibrator, and a secondary side control circuit having a closed control loop that detects secondary vibration generated in the vibrator due to an angular velocity applied to the vibrator and configured to correct the sensor output by adding an offset value to the closed control loop, wherein the primary side control circuit is configured to be able to switch the electrode that induces the primary vibration in the vibrator, and the secondary side control circuit is configured to be able to switch the electrode that detects the secondary vibration of the vibrator, and the offset value after switching and the offset value before switching are symmetrical with respect to a predetermined reference value.

[0012] As described above, the vibration type angular velocity sensor according to the first aspect of the present invention is configured such that the electrodes that induce the primary vibration in the vibrator can be switched by the primary side control circuit, and the electrodes that detect the secondary vibration of the vibrator can be switched by the secondary side control circuit, and the offset value after switching and the offset value before switching are symmetrical with respect to a predetermined reference value. As a result, the offset value becomes symmetrical with respect to the predetermined reference value before and after switching, so that it is possible to prevent the symmetry of the control of the vibration type angular velocity sensor before and after switching from being lost. As a result, it is possible to prevent the temperature fluctuation component of the bias that remains without being canceled from becoming large.

[0013] In the vibration type angular velocity sensor according to the first aspect, the secondary control circuit is preferably configured to include a loop filter in a closed control loop and to correct the sensor output by adding an offset value to the input of the loop filter. Here, the output in the closed control loop corresponds to the output of the loop filter. The output of the loop filter is inversely proportional to the gain of the vibrator, which depends on temperature due to the feedback operation of the closed control loop. In the present invention, focusing on this point, an offset value is added to the input of the loop filter, thereby making it possible to reduce errors caused by crosstalk, which are inversely proportional to the first power and / or the square of the gain of the vibrator.

[0014] In the vibration type angular velocity sensor according to the first aspect, preferably, when the offset value before switching is a, the offset value after switching is −a, which is obtained by inverting the polarity of the offset value before switching. With this configuration, the offset value becomes symmetrical about zero before and after switching, so that it is possible to suppress the symmetry of the control of the vibration type angular velocity sensor before and after switching from being destroyed.

[0015] In the vibration type angular velocity sensor according to the first aspect, preferably, if the provisional offset value before switching is a, the provisional offset value after switching is -a, and the provisional offset value for the median value of the sensor output before switching and the sensor output after switching is b, the offset value before switching is a+b, and the offset value after switching is -a+b. With this configuration, the offset value before and after switching is symmetrical with respect to b, so that it is possible to suppress the symmetry of the control of the vibration type angular velocity sensor before and after switching from being broken. Also, since the offset value before and after switching is symmetrical with respect to the offset value b with respect to the median value of the sensor output before and after switching, it is possible to suppress the symmetry of the control of the vibration type angular velocity sensor before and after switching from being broken while reducing the gradient of the residual bias component with respect to the environmental temperature. Here, "provisional" means an offset value at an intermediate stage until the final offset value is obtained.

[0016] In the vibration type angular velocity sensor according to the first aspect, preferably, when the sensor output is corrected in an analog manner, a first offset value based on the output of the primary control circuit inversely proportional to the temperature change of the gain of the vibrator from the secondary control circuit and a second offset value based on a constant signal independent of temperature are added to the closed control loop of the secondary control circuit to correct the sensor output inversely proportional to the square of the temperature change of the gain of the vibrator from the secondary control circuit, and the sensor output is corrected by adjusting the amount of addition of the first offset value and the second offset value. Here, when the second offset value based on a constant signal independent of temperature is added to the closed control loop of the secondary control circuit, the output of the secondary control circuit has a characteristic inversely proportional to the gain of the vibrator that depends on temperature. Similarly, since the output of the primary control circuit also has a characteristic inversely proportional to the gain of the vibrator due to the feedback operation of the closed control loop, by adding a first offset value based on the output of the primary control circuit having a characteristic inversely proportional to the gain of the vibrator to the closed control loop of the secondary control circuit, the output of the secondary control circuit has a characteristic inversely proportional to the square of the gain of the vibrator. That is, by adding a first offset value corresponding to the square of the gain of the vibrator and a second offset value corresponding to the square of the gain of the vibrator, and by adjusting the amount of addition of the first offset value and the second offset value, correction inversely proportional to the square of the gain of the vibrator and correction inversely proportional to the square of the gain of the vibrator can be performed.

[0017] In this case, it is preferable to set the temperature-dependent gain of the transducer to G R (T), and A, B, and C are constant values ​​that are independent of temperature. The sum of the error in the sensor output that occurs in the closed control loop of the secondary control circuit due to the error signal generated from the circuit blocks that make up the secondary control circuit and the error in the sensor output that occurs in the closed control loop of the secondary control circuit due to crosstalk from the primary control circuit to the secondary control circuit is V. Out_Total_Error is expressed by the following formula, and the first term of the formula, A / G R 2In order to reduce (T), the amount of the first offset value based on the output of the primary side control circuit that depends on temperature, which is inversely proportional to the temperature change of the gain of the vibrator, is adjusted, and the second term of the following formula, B / G R The sensor output is corrected in an analog manner by adjusting the amount of the second offset value based on a constant signal independent of temperature so as to reduce (T). With this configuration, it is possible to reduce both the first-order (the first power of the gain of the vibrator) and second-order (the square of the gain of the vibrator) components of the sensor output error, thereby reliably improving the accuracy of the correction. Although a constant value C remains, since C is a constant value independent of temperature, it does not affect the sensor output error due to temperature changes and does not pose a problem in terms of correction.

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[0018] In the vibration type angular velocity sensor according to the first aspect, preferably, when the sensor output is digitally corrected, the output of the primary side control circuit, which is dependent on temperature and inversely proportional to the temperature change of the gain of the vibrator, is quantized, and an offset value that reduces the error of the sensor output due to temperature change is added to the secondary side control circuit for the quantized output of the primary side control circuit, thereby correcting the sensor output. With this configuration, the sensor output can be corrected simply by adding the offset value that reduces the error of the sensor output due to temperature change to the secondary side control circuit, so that the configuration of the vibration type angular velocity sensor can be simplified, unlike the case of adding an offset value other than the offset value based on the output of the primary side control circuit dependent on temperature.

[0019] In the vibration type angular velocity sensor according to the first aspect, the vibrator preferably includes a ring-shaped vibrator. Here, since the ring-shaped vibrator has a symmetrical shape, the vibration mode caused by the primary control circuit and the vibration mode caused by the secondary control circuit are similar. Therefore, if the present invention is applied to a vibration type angular velocity sensor including a ring-shaped vibrator, it is not necessary to consider the influence of the difference in vibration modes, and therefore the sensor output can be easily corrected.

[0020] In the vibration type angular velocity sensor according to the first aspect, the primary control circuit preferably includes a first switch provided on the input side of the signal to the vibrator and a second switch provided on the output side of the signal from the vibrator, and the secondary control circuit preferably includes a third switch provided on the input side of the signal to the vibrator and a fourth switch provided on the output side of the signal from the vibrator, and the first switch and the second switch are switched to switch the electrode that induces the primary vibration in the vibrator by the primary control circuit, and the third switch and the fourth switch are switched to switch the electrode that detects the secondary vibration of the vibrator by the secondary control circuit. With this configuration, by switching the first switch to the fourth switch, it is possible to easily switch between the electrode that induces the primary vibration in the vibrator by the primary control circuit and the electrode that detects the secondary vibration of the vibrator by the secondary control circuit. Effect of the Invention

[0021] According to the present invention, as described above, it is possible to prevent the temperature fluctuation component of the bias that remains without being cancelled from increasing. [Brief description of the drawings]

[0022] [Figure 1] 1 is a block diagram showing a configuration of a vibration type angular velocity sensor according to a first embodiment. [Diagram 2] 5A to 5C are diagrams for explaining correction of the sensor output based on a constant signal independent of temperature in the vibration type angular velocity sensor according to the first embodiment. [Diagram 3]5A and 5B are diagrams for explaining correction of the sensor output based on the output of the primary side control circuit dependent on temperature in the vibration type angular velocity sensor according to the first embodiment. [Figure 4] FIG. 13 is a diagram showing the relationship between temperature and bias component. [Diagram 5] FIG. 1 shows the relationship between temperature and bias component after the sensor output is corrected by the offset value (1). [Figure 6] (a) Graph (2) showing the relationship between temperature and bias component after sensor output correction using an offset value, and (b) Graph (3) showing the relationship between temperature and bias component after sensor output correction using an offset value. [Figure 7] FIG. 4 shows the relationship between temperature and bias component after the sensor output is corrected by the offset value. [Figure 8] FIG. 11 is a block diagram showing the configuration of a vibration type angular velocity sensor according to a second embodiment. [Figure 9] 13 is a diagram for explaining correction of the sensor output of the vibration type angular velocity sensor according to the second embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] (First embodiment) First, the configuration of a vibration type angular velocity sensor 100 according to a first embodiment will be described with reference to Fig. 1. In this first embodiment, an example in which correction is performed by analog processing of the sensor output of the vibration type angular velocity sensor 100 will be described.

[0025] 1, the vibration type angular velocity sensor 100 includes a vibrator 1, a primary side control circuit 2 having a closed control loop for driving the vibrator 1, and a secondary side control circuit 3 having a closed control loop for detecting and outputting secondary vibration when an angular velocity is applied to the vibrator 1 driven by the primary side control circuit 2. Here, in the first embodiment, the vibrator 1 is a ring-shaped vibrator 1.

[0026] The primary side control circuit 2 includes an amplifier circuit 21, a synchronous detection circuit 22, a loop filter 23, a modulation circuit 24, a drive circuit 25, a PLL (Phase Locked Loop) circuit (phase-locked circuit) 26, and a reference signal generation circuit 27. The vibrator 1, the amplifier circuit 21, the synchronous detection circuit 22, the loop filter 23, the modulation circuit 24, and the drive circuit 25 are connected in this order to form a closed control loop. The loop filter 23 is, for example, an integral filter. The loop filter 23 is an example of the "primary side loop filter" in the claims.

[0027] The secondary side control circuit 3 includes an amplifier circuit 31, a synchronous detection circuit 32, an adder circuit 33, a loop filter 34, a modulation circuit 35, a drive circuit 36, and an amplifier circuit 37. The vibrator 1, the amplifier circuit 31, the synchronous detection circuit 32, the adder circuit 33, the loop filter 34, the modulation circuit 35, and the drive circuit 36 ​​are connected in this order to form a closed control loop. The adder circuit 33 is configured by a general addition / subtraction circuit using an operational amplifier. The loop filter 34 is, for example, an integral filter. The output of the loop filter 34 is input to the amplifier circuit 37. The signal output from the amplifier circuit 37 is output to the outside as the sensor output of the vibration type angular velocity sensor 100.

[0028] Here, in the first embodiment, the vibration type angular velocity sensor 100 is configured such that the electrode 50 that induces the primary vibration in the vibrator 1 can be switched by the primary side control circuit 2, and the electrode 50 that detects the secondary vibration of the vibrator 1 can be switched by the secondary side control circuit 3. Specifically, in the primary side control circuit 2, a switch 41 is provided on the input side of the signal to the vibrator 1, and a switch 42 is provided on the output side (output side of the amplifier circuit 21) of the signal from the vibrator 1. In addition, in the secondary side control circuit 3, a switch 43 is provided on the input side of the signal to the vibrator 1, and a switch 44 is provided on the output side (output side of the amplifier circuit 31) of the signal from the vibrator 1. FIG. 1 shows a state in which the switch 41 and the switch 42 connect the electrode 50 arranged on the upper side of the vibrator 1 to the primary side control circuit 2, and the switch 43 and the switch 44 connect the electrode 50 arranged on the lower side of the vibrator 1 to the secondary side control circuit 3. Note that the "upper side" and the "lower side" respectively refer to the "upper side" and the "lower side" for the purpose of explanation in FIG. 1, and do not refer to the "upper side" and the "lower side" in the actual vibrator 1. Furthermore, the switches 41 and 42 are examples of the "first switch" and the "second switch" respectively in the claims. Furthermore, the switches 43 and 44 are examples of the "third switch" and the "fourth switch" respectively in the claims.

[0029] In the first embodiment, the switch 41 and the switch 42 are switched to switch the electrode 50 that induces the primary vibration in the vibrator 1 by the primary control circuit 2. The switch 43 and the switch 44 are switched to switch the electrode 50 that detects the secondary vibration of the vibrator 1 by the secondary control circuit 3. Specifically, the state shown in FIG. 1 in which the switch 41 and the switch 42 connect the electrode 50 arranged on the upper side of the vibrator 1 to the primary control circuit 2 and the switch 43 and the switch 44 connect the electrode 50 arranged on the lower side of the vibrator 1 to the secondary control circuit 3 is switched to a state in which the switch 41 and the switch 42 connect the electrode 50 arranged on the upper side of the vibrator 1 to the secondary control circuit 3 and the switch 43 and the switch 44 connect the electrode 50 arranged on the lower side of the vibrator 1 to the primary control circuit 2. As a result, the primary-side control circuit 2 switches the electrode 50 that induces the primary vibration in the vibrator 1, and the secondary-side control circuit 3 switches the electrode 50 that detects the secondary vibration of the vibrator 1. Note that the "upper side" and "lower side" respectively mean the "upper side" and "lower side" for the purposes of explanation in FIG. 1, and do not mean the "upper side" and "lower side" in the actual vibrator 1.

[0030] The vibration type angular velocity sensor 100 is also provided with addition / subtraction amount adjustment circuits 4a and 4b to which the output from the primary side control circuit 2 (output from the loop filter 23) is input. The addition / subtraction amount adjustment circuits 4a and 4b are configured to adjust the magnitude of the output of the loop filter 23 of the primary side control circuit 2, which depends on temperature, and input the adjusted output (provisional first offset value) to the adder circuit 33 of the secondary side control circuit 3. For example, in the addition / subtraction amount adjustment circuits 4a and 4b, the addition amount of the provisional first offset value is adjusted by dividing the voltage using a potentiometer (volume resistor) or the like.

[0031] The vibration type angular velocity sensor 100 is also provided with an addition / subtraction amount adjustment circuit 5a to which a constant signal S1 that is independent of temperature is input. The addition / subtraction amount adjustment circuit 5a is configured to adjust the magnitude of the constant signal S1 and input the adjusted constant signal S1 (a provisional second offset value) to the adder circuit 33 of the secondary side control circuit 3. For example, in the addition / subtraction amount adjustment circuit 5a, the addition amount of the constant signal S1 is adjusted by dividing the voltage using a potentiometer (volume resistor) or the like.

[0032] The vibration type angular velocity sensor 100 is also provided with an addition / subtraction amount adjustment circuit 5b to which a constant signal S2 that is independent of temperature is input. The addition / subtraction amount adjustment circuit 5b is configured to adjust the magnitude of the constant signal S2 and input the adjusted constant signal S2 (a provisional second offset value) to the adder circuit 33 of the secondary side control circuit 3. For example, in the addition / subtraction amount adjustment circuit 5b, the addition amount of the constant signal S2 is adjusted by dividing the voltage using a potentiometer (volume resistor) or the like.

[0033] Here, in the first embodiment, when the sensor output is corrected in an analog manner, a first offset value based on the output of the primary control circuit 2 (output of the loop filter 23) which is inversely proportional to the temperature change of the gain of the vibrator 1, and a second offset value based on a constant signal which is independent of temperature are added to the closed control loop of the secondary control circuit 3 (input of the loop filter 34 of the secondary control circuit 3) in order to correct the sensor output from the secondary control circuit 3 which is inversely proportional to the square of the temperature change of the gain of the vibrator 1, and the amount of addition of the first offset value and the amount of addition of the second offset value are adjusted by the addition / subtraction amount adjustment circuits 4a and 4b and the addition / subtraction amount adjustment circuits 5a and 5b, respectively, to correct the sensor output (output from the secondary control circuit 3). The sensor output is corrected by determining and adding a first offset value and a second offset value so as to reduce an error in the sensor output that occurs in the closed control loop of the secondary control circuit 3 due to an error signal generated from a circuit block that constitutes the secondary control circuit 3, and an error in the sensor output that occurs in the closed control loop of the secondary control circuit 3 due to crosstalk (signal crossing) from the primary control circuit 2 to the secondary control circuit 3.

[0034] In the first embodiment, the offset values ​​after switching (the first offset value and the second offset value) and the offset values ​​before switching are symmetrical with respect to a predetermined reference value. In other words, the absolute value of the difference between the offset value added to the closed control loop before switching and the predetermined reference value is configured to be substantially equal to the absolute value of the difference between the offset value added to the closed control loop after switching and the predetermined reference value.

[0035] Specifically, in the first embodiment, if a is a provisional offset value before switching, -a is a provisional offset value after switching, and b is a provisional offset value relative to the median value between the sensor output before switching and the sensor output after switching, the offset value before switching is a+b, and the offset value after switching is -a+b. The provisional offset value a means a provisional first offset value a1, which will be described later, and a provisional second offset value a2, which will be described later. The provisional offset value b means a provisional first offset value b1, which will be described later, and a provisional second offset value b2, which will be described later. The provisional offset value b relative to the median value is an example of a "predetermined reference value" in the claims.

[0036] In detail, as shown in FIG. 1, an addition / subtraction amount adjustment circuit 4a and an addition / subtraction amount adjustment circuit 4b are provided on the output side of the primary side control circuit 2. An inversion circuit 51 and a switch 52 are provided on the output side of the addition / subtraction amount adjustment circuit 4a. The switch 52 is configured to be able to switch between a state in which it is connected to the addition / subtraction amount adjustment circuit 4a and a state in which it is connected to the inversion circuit 51. Then, as shown in FIG. 1, when the switch 52 is connected to the addition / subtraction amount adjustment circuit 4a, the output (a1) from the addition / subtraction amount adjustment circuit 4a and the output (b1) from the addition / subtraction amount adjustment circuit 4b are input to the addition circuit 33. That is, a1+b1 is added to the secondary side control circuit 3 as a first offset value. Also, when the switch 52 is connected to the inversion circuit 51, the output (-a1) from the inversion circuit 51 and the output (b1) from the addition / subtraction amount adjustment circuit 4b are input to the addition circuit 33. That is, −a1+b1 is added as a first offset value to the secondary-side control circuit 3. How to determine a1 and b1 will be described later.

[0037] Moreover, an inversion circuit 45 and a switch 46 are provided on the output side of the addition / subtraction amount adjustment circuit 5b. The switch 46 is configured to be able to switch between a state where it is connected to the addition / subtraction amount adjustment circuit 5b and a state where it is connected to the inversion circuit 45. Then, as shown in FIG. 1, when the switch 46 is connected to the addition / subtraction amount adjustment circuit 5b, the output (a2) from the addition / subtraction amount adjustment circuit 5b and the output (b2) from the addition / subtraction amount adjustment circuit 5a are input to the addition circuit 33. That is, a2+b2 is added to the secondary side control circuit 3 as a second offset value. When the switch 46 is connected to the inversion circuit 45, the output (-a2) from the inversion circuit 45 and the output (b2) from the addition / subtraction amount adjustment circuit 5a are input to the addition circuit 33. That is, -a2+b2 is added to the secondary side control circuit 3 as a second offset value. The method of determining a2 and b2 will be described later.

[0038] (No switching configuration) Next, correction of the sensor output of the vibration type angular velocity sensor 100 will be described in detail with reference to Fig. 1. Below, a case will be described in which the electrodes 50 that induce the primary vibration in the vibrator 1 are not switched by the primary side control circuit 2, and the electrodes 50 that detect the secondary vibration of the vibrator 1 are not switched by the secondary side control circuit 3 (i.e., the configuration of Japanese Patent No. 6463335).

[0039] First, the output error of the vibration type angular velocity sensor 100 to be corrected will be described. The output error of the vibration type angular velocity sensor 100 includes an error in the sensor output of the vibration type angular velocity sensor 100 caused by an error signal generated from a circuit block constituting the secondary side control circuit 3, and an error in the sensor output of the vibration type angular velocity sensor 100 caused by an influence (crosstalk) from the primary side control circuit 2. The component of the error signal (error component) generated from the circuit block constituting the secondary side control circuit 3 is assumed to be a constant value that does not have temperature dependency. Generally, in a feedback circuit, the output signal from each circuit is represented by a value obtained by dividing the input signal input to each circuit by a feedback gain (output signal = input signal x 1 / (feedback gain)).

[0040] As described in Japanese Patent No. 6463335, the total V is the error of the sensor output generated in the closed control loop of the secondary control circuit 3 due to an error signal generated from the circuit block constituting the secondary control circuit 3 and the error of the sensor output generated in the closed control loop of the secondary control circuit 3 due to crosstalk from the primary control circuit 2 to the secondary control circuit 3. Out_Total_Error is expressed by the following formula 3. Note that A, B, and C are constant values ​​(coefficients) that do not depend on temperature.

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[0041] Next, the error V of the sensor output of the vibration type angular velocity sensor 100 expressed by the above formula 3 is Out_Total_Error A specific example of correcting the sensor output in an analog manner will now be described.

[0042] First, a V In_Const_Corr (the second offset value) is added. In this case, the sensor output V Out_Const_Corr is expressed by the following formula 4. In the following formula 4, G SD is the gain in the drive circuit 36 ​​(Secondary Drive Amplifier Gain), and is a value that does not depend on temperature. SR (T) is the gain in transducer 1 (Secondary Resonator Gain). G SP is the gain in the amplifier circuit 31 (Secondary Pick off Amplifier Gain), and is a value independent of temperature.

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[0043] Here, when a second offset value based on a constant signal independent of temperature is added to the input of the loop filter 34, the sensor output VOut_Const_Corr is the temperature dependent gain G R (T). Note that p in the above formula 4 is a constant value. And, p in the above formula 4 and the second term in the above formula 3, B / G R V so that the magnitude of B in (T) is equal to (p=-B). In_Const_Corr By adjusting the (second offset value) by the addition / subtraction amount adjustment circuit 5a, the second term of the above formula 3, B / G R That is, the gain G (T) depending on the temperature in the above formula 3 is cancelled by adjusting the second offset value based on a constant signal that is not dependent on temperature and adding it to the input of the loop filter 34. R It becomes possible to cancel out the term inversely proportional to the first power of (T).

[0044] In addition, the output V of the loop filter 23 of the primary side control circuit 2, which depends on temperature, AGC is expressed by the following formula 5. Note that the output V of the loop filter 23 AGC is the output of the loop filter 23 taking into account the closed control loop, and is a value that depends on temperature.

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[0045] Here, in the analog correction according to the first embodiment, the V In_Const_Corr (second offset value) plus the output V AGC A value (first offset value) obtained by multiplying by a certain ratio q is added to the input (path 2) of the loop filter 34 of the secondary side control circuit 3. The sensor output V of the vibration type angular velocity sensor 100 when this first offset value is added is Out_AGC_Corr is expressed by the following Equation 6.

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[0046] Here, when the first offset value based on the output of the primary side control circuit 2, which depends on temperature, is added to the input of the loop filter 34, the sensor output V Out_AGC_Corr is the temperature dependent gain G R The value is inversely proportional to the square of (T). Note that r in the above formula 6 is a constant value. And, r in the above formula 6 and G in the above formula 3 R A / G of the first term including the square of (T) R 2 By adjusting q by the addition / subtraction adjustment circuit 4b so that the magnitude of A in (T) is equal to (r=-A), the first term of the above formula 3, A / G R 2 (T) is canceled. That is, when the sensor output of the vibration type angular velocity sensor 100 is not corrected, the sensor output becomes a value obtained by adding the error represented by the above formula 3 to the original sensor output, whereas in the first embodiment, by adding the first offset value and the second offset value, the sensor output of the vibration type angular velocity sensor 100 becomes a value obtained by adding a constant value C to the original sensor output.

[0047] Note that C in Equation 3 is a constant value that is independent of temperature, and does not pose a problem in terms of correction. Also, the coefficients A, B, and C in Equation 3 above are calculated by measuring (actually measuring) the sensor output of the vibration type angular velocity sensor 100 before correction (before compensation) at each temperature, and approximating the measured data with a polynomial using the least squares method. Note that the coefficients A, B, and C are calculated for each vibration type angular velocity sensor 100 (for each product).

[0048] Thus, the first term of Equation 3, A / G R 2 (T) (Temperature-dependent gain G R The amount of addition of the first offset value based on the output of the primary side control circuit 2 that depends on temperature is adjusted so that the second term of Equation 3, B / G R (T) (Temperature-dependent gain G RThe sensor output is corrected in an analog manner by adjusting the amount of the second offset value, which is based on a constant signal that is independent of temperature, to make (the term inversely proportional to T) zero.

[0049] That is, as shown in FIG. 2, by adding the second offset value based on a constant signal that is not dependent on temperature, the error of the sensor output of the vibration type angular velocity sensor 100 is reduced by 1 / G. R (T) (temperature-dependent gain G R By canceling the component (the second term in Equation 3) that is inversely proportional to (T), the sensor output (dotted line in FIG. 2) that had a temperature-dependent characteristic becomes approximately constant (solid line in FIG. 2). However, as shown in FIG. 3, even the sensor output that has been made approximately constant still has a temperature-dependent characteristic (dotted line in FIG. 3) microscopically. Therefore, by adding a first offset value based on the output of the primary-side control circuit 2 that is dependent on temperature, the sensor output of the vibration type angular velocity sensor 100 becomes 1 / G R 2 (T) (temperature-dependent gain G R By canceling the component (first term in Equation 3) that is inversely proportional to the square of (T), the sensor output becomes approximately constant (solid line in FIG. 3) independent of temperature. As a result, it becomes possible to improve the accuracy of correction. Also, when the sensor output of the vibration type angular velocity sensor 100 is corrected in an analog manner, unlike when it is corrected digitally (the signal is a discrete value), the signal is a continuous value, so it becomes possible to suppress step-like changes in the sensor output of the vibration type angular velocity sensor 100 (make the sensor output a continuous value).

[0050] (Configuration with switching) Next, we will explain the offset value of the first embodiment, in which the electrode 50 that induces primary vibration in the vibrator 1 can be switched by the primary side control circuit 2, and the electrode 50 that detects secondary vibration of the vibrator 1 can be switched by the secondary side control circuit 3.

[0051] As shown in FIG. 4, in general, in the vibration type angular velocity sensor 100, the bias component (vertical axis) of the angular velocity detected by the vibration type angular velocity sensor 100 changes with respect to the change in temperature (horizontal axis). Also, the change in the bias component before switching (P in FIG. 4) is different from the change in the bias component after switching (S in FIG. 4). Then, as shown in FIG. 5, before switching, the first offset value and the second offset value are added so as to cancel the first and second terms of the above-mentioned formula 3, thereby reducing the temperature change in the sensor output (P in FIG. 5). Also, after switching, the first offset value and the second offset value are added so as to cancel the first and second terms of the above-mentioned formula 3, thereby reducing the temperature change in the sensor output (S in FIG. 5). Note that P and S in FIG. 5 are not symmetrical with respect to the line segment along the horizontal axis (the dashed line in FIG. 5), so the temperature fluctuation component of the difference between P and S in FIG. 5 does not become zero. In this way, if the first offset value and the second offset value are determined so as to cancel the first and second terms of the above equation 3 individually before and after switching, the temperature fluctuation component of the difference between P and S in Figure 5 will not become zero.

[0052] Therefore, as shown in Fig. 6(a), the provisional first offset value a1 and the provisional second offset value a2 before and after the switching are determined so that the temperature fluctuation component of the difference is minimized and the polarity of the offset value is inverted before and after the switching. When the provisional first offset value a1 and the provisional second offset value a2 are used before the switching, the first and second terms of the above formula 3 are not canceled, so the bias component has a gradient with respect to temperature before the switching. Similarly, when the provisional first offset value -a1 and the provisional second offset value -a2 are used after the switching, the first and second terms of the above formula 3 are not canceled, so the bias component has a gradient with respect to temperature after the switching.

[0053] Therefore, as shown in FIG. 6(b), a provisional first offset value b1 and a provisional second offset value b2 are determined so as to cancel the first and second terms of the above formula 3 for the median (M in FIG. 4) of the change in the bias component before switching (P in FIG. 4) and the change in the bias component after switching (S in FIG. 4). Then, the first offset value before switching is a1+b1, the second offset value is a2+b2, and the first offset value after switching is -a1+b1, and the second offset value is -a2+b2. As a result, the first offset value becomes symmetrical with respect to the provisional first offset value b1 with respect to the median before and after switching, and the second offset value becomes symmetrical with respect to the provisional second offset value b2 with respect to the median. As a result, as shown in FIG. 7, the temperature gradient of both the change in the bias component before switching (P in FIG. 7) and the change in the bias component after switching (S in FIG. 7) becomes small. As a result, it becomes possible to reduce the temperature gradient of the bias component while reducing the difference (residual bias component) between P and S in FIG. 7.

[0054] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained. In the following description, the Q value (a dimensionless number indicating the state of vibration) is described as having a characteristic that is roughly inversely proportional to the temperature.

[0055] In the first embodiment, as described above, the vibration type angular velocity sensor 100 is configured to be able to switch the electrodes 50 that induce the primary vibration in the vibrator 1 by the primary side control circuit 2, and is configured to be able to switch the electrodes 50 that detect the secondary vibration of the vibrator 1 by the secondary side control circuit 3, and the offset value after switching and the offset value before switching are symmetrical with respect to a predetermined reference value. As a result, since the offset value becomes symmetrical with respect to the predetermined reference value before and after switching, it is possible to suppress the loss of symmetry in the control of the vibration type angular velocity sensor 100 before and after switching. As a result, it is possible to suppress the increase in the temperature fluctuation component of the bias that remains without being canceled.

[0056] Also, in the first embodiment, as described above, the secondary-side control circuit 3 includes the loop filter 34 in the closed control loop, and is configured to correct the sensor output by adding an offset value to the input of the loop filter 34. Here, the output in the closed control loop corresponds to the output of the loop filter. The output of the loop filter is inversely proportional to the gain of the vibrator 1, which depends on the temperature due to the feedback operation of the closed control loop. In the first embodiment, focusing on this point, an offset value is added to the input of the loop filter 34, thereby making it possible to reduce errors caused by crosstalk that are inversely proportional to the first power and / or the square of the gain of the vibrator 1.

[0057] In the first embodiment, as described above, if the offset value before switching is a, the offset value after switching is −a, which is the inverse of the polarity of the offset value before switching. As a result, the offset value becomes symmetrical with respect to zero before and after switching between the electrode 50 that induces the primary vibration in the vibrator 1 by the primary control circuit 2 and the electrode 50 that detects the secondary vibration of the vibrator 1 by the secondary control circuit 3, so that it is possible to suppress the loss of symmetry in the control of the vibration type angular velocity sensor 100 before and after switching.

[0058] In the first embodiment, as described above, if the provisional offset value before switching is a, the provisional offset value after switching is -a, and the provisional offset value for the median value of the sensor output before switching and the sensor output after switching is b, the offset value before switching is a+b, and the offset value after switching is -a+b. As a result, the offset value becomes symmetrical with respect to b before and after switching between the electrode 50 that induces the primary vibration in the vibrator 1 by the primary side control circuit 2 and the electrode 50 that detects the secondary vibration of the vibrator 1 by the secondary side control circuit 3, so that it is possible to suppress the symmetry of the control of the vibration type angular velocity sensor 100 before and after switching from being broken. In addition, the offset value before and after switching becomes symmetrical with respect to the offset value b with respect to the median value of the sensor output before and after switching, so that it is possible to suppress the symmetry of the control of the vibration type angular velocity sensor 100 before and after switching from being broken while reducing the gradient of the residual bias component with respect to the environmental temperature.

[0059] In the first embodiment, as described above, when the sensor output is corrected in an analog manner, in order to correct the sensor output inversely proportional to the square of the temperature change of the gain of the vibrator 1 from the secondary control circuit 3, a first offset value based on the output of the primary control circuit 2 inversely proportional to the temperature change of the gain of the vibrator 1 and a second offset value based on a constant signal independent of temperature are added to the closed control loop of the secondary control circuit 3, and the sensor output is corrected by adjusting the amount of addition of the first offset value and the second offset value. Here, when the second offset value based on a constant signal independent of temperature is added to the closed control loop of the secondary control circuit 3, the output of the secondary control circuit 3 has a characteristic inversely proportional to the gain of the vibrator 1 that depends on temperature. Similarly, the output of the primary side control circuit 2 also has a characteristic inversely proportional to the gain of the vibrator 1 due to the feedback operation of the closed control loop, so by adding a first offset value based on the output of the primary side control circuit 2 having a characteristic inversely proportional to the gain of the vibrator 1 to the closed control loop of the secondary side control circuit 3, the output of the secondary side control circuit 3 has a characteristic inversely proportional to the square of the gain of the vibrator 1. That is, by adding a first offset value corresponding to the square of the gain of the vibrator 1 and a second offset value corresponding to the square of the gain of the vibrator 1, and correcting the sensor output by adjusting the addition amounts of the first offset value and the second offset value, it is possible to perform correction inversely proportional to the square of the gain of the vibrator 1 and correction inversely proportional to the square of the gain of the vibrator 1.

[0060] In the first embodiment, as described above, the gain that depends on the temperature of the transducer 1 is G R (T), and A, B, and C are constant values ​​that are independent of temperature. The sum of the error in the sensor output that occurs in the closed control loop of the secondary control circuit 3 due to the error signal generated from the circuit blocks that make up the secondary control circuit 3 and the error in the sensor output that occurs in the closed control loop of the secondary control circuit 3 due to crosstalk from the primary control circuit 2 to the secondary control circuit 3 is V. Out_Total_Erroris expressed by the above formula 3, and the first term of the above formula 3, A / G R 2 In order to reduce (T), the amount of addition of the first offset value based on the output of the primary side control circuit 2 that depends on temperature and is inversely proportional to the temperature change of the gain of the vibrator 1 is adjusted, and the second term of the above formula 3, B / G R The sensor output is corrected in an analog manner by adjusting the amount of the second offset value based on a constant signal independent of temperature so as to reduce (T). This makes it possible to reduce both the first-order (the first power of the gain of oscillator 1) and second-order (the square of the gain of oscillator 1) components of the sensor output error, thereby reliably improving the accuracy of the correction. Although a constant value C remains, C is a constant value independent of temperature and does not affect the sensor output error due to temperature changes, so this does not pose a problem in terms of correction.

[0061] In the first embodiment, as described above, the vibrator 1 includes a ring-type vibrator 1. Here, since the ring-type vibrator 1 has a symmetrical shape, the vibration mode caused by the primary-side control circuit 2 and the vibration mode caused by the secondary-side control circuit 3 are similar. Therefore, if the present invention is applied to a vibration-type angular velocity sensor 100 including the ring-type vibrator 1, it is not necessary to consider the influence of the difference in vibration modes, and therefore the sensor output can be easily corrected.

[0062] Also, in the first embodiment, as described above, by switching switches 41 and 42, the part of vibrator 1 that induces the primary vibration is switched by primary side control circuit 2, and by switching switches 43 and 44, the part of vibrator 1 that detects the secondary vibration is switched by secondary side control circuit 3. As a result, by switching switches 41 to 43, it is possible to easily switch between electrode 50 that induces the primary vibration in vibrator 1 by primary side control circuit 2 and electrode 50 that detects the secondary vibration of vibrator 1 by secondary side control circuit 3.

[0063] Second embodiment Next, a configuration of a vibration type angular velocity sensor 101 according to a second embodiment will be described with reference to Fig. 8. In the second embodiment, an example in which correction is performed by digitally processing the output of the loop filter 23 of the primary side control circuit 2 will be described.

[0064] 8, the vibration type angular velocity sensor 101 includes a vibrator 1, a primary side control circuit 2, a secondary side control circuit 3, an AD conversion circuit 6, a correction calculation processing unit 7, and a DA conversion circuit 8. The configurations of the vibrator 1, the primary side control circuit 2, and the secondary side control circuit 3 are similar to those of the first embodiment.

[0065] Also, similarly to the first embodiment, the vibration type angular velocity sensor 101 is configured to be able to switch between an electrode 50 that induces a primary vibration in the vibrator 1 by the primary side control circuit 2 and an electrode 50 that detects a secondary vibration of the vibrator 1 by the secondary side control circuit 3. Specifically, in the primary side control circuit 2, a switch 41 is provided on the input side of the signal to the vibrator 1, and a switch 42 is provided on the output side of the signal from the vibrator 1 (the output side of the amplifier circuit 21). Also, in the secondary side control circuit 3, a switch 43 is provided on the input side of the signal to the vibrator 1, and a switch 44 is provided on the output side of the signal from the vibrator 1 (the output side of the amplifier circuit 31).

[0066] The AD conversion circuit 6 is configured to receive an analog signal dependent on temperature output from the loop filter 23 of the primary-side control circuit 2, convert (quantize) the analog signal into a digital signal, and output the digital signal to the correction calculation processing unit 7. In the second embodiment, the correction calculation processing unit 7 is configured to output an offset value for the quantized output of the primary-side control circuit 2 (output from the AD conversion circuit 6) to the DA conversion circuit 8, the offset value reducing an error in the sensor output due to temperature changes. The DA conversion circuit 8 is configured to convert the offset value into an analog signal, and add it to the input of the loop filter 34 of the secondary-side control circuit 3. In this way, the vibration type angular velocity sensor 101 is configured to correct the sensor output.

[0067] Next, the case where the sensor output is digitally corrected will be specifically described with reference to FIGS.

[0068] First, by measuring the sensor output of the vibration type angular velocity sensor 101 while sweeping (changing to various values) the offset value (correction value) input to the addition circuit 33 of the secondary side control circuit 3, similarly to the first embodiment, offset values ​​(y1, y2, see FIG. 9) at each temperature (T1, T2, see FIG. 9) before and after switching are searched for such that the residual of the temperature fluctuation component of the bias (difference before and after switching) is minimized before and after switching and the polarity of the offset value is reversed before and after switching. Also, offset values ​​(z1, z2, see FIG. 9) at each temperature (T1, T2, see FIG. 9) at which the error of the sensor output of the vibration type angular velocity sensor 101 (error corresponding to the error defined by the above formula 3) becomes 0 or approximately 0 with respect to the median value of the bias component before and after switching are searched for.

[0069] Next, the quantized output from the primary-side control circuit 2 (loop filter 23) at each temperature is taken as x, and the offset value at which the residual of the temperature fluctuation component of the bias (the difference before and after switching) is the smallest is taken as y, and the data shown in Fig. 9 is polynomial-approximated by the least squares method to obtain (calculate) the following formula 7 (l, m, and n are constant coefficients). In the second embodiment, a second-order polynomial is used as shown in the following formula 7.

number

[0070] Similarly, assuming that the quantized output from the primary side control circuit 2 (loop filter 23) at each temperature is x, the following formula 8 is obtained as the offset value for the median value of the bias component before and after the switching.

number

[0071] As a result, the relational expressions (the above formulas 7 and 8) between the offset value at each temperature and the quantized output of the primary side control circuit 2 at each temperature are found in advance (before the actual use of the vibration type angular velocity sensor 101). The calculation of the relational expressions is performed for each vibration type angular velocity sensor 101 (for each product). When the vibration type angular velocity sensor 101 is actually used, the quantized output (x) of the primary side control circuit 2 is calculated by software in the correction calculation processing unit 7 using the above formulas 7 and 8, and the obtained offset value (y+z before switching, -y+z after switching) is added to the secondary side control circuit 3, thereby performing correction. That is, when the sensor output is digitally corrected, calculations are always performed using the relational expressions (formulas 7 and 8), and correction is always performed according to the quantized output of the primary side control circuit 2.

[0072] In the second embodiment, the following effects can be obtained.

[0073] In the second embodiment, as described above, when the sensor output is digitally corrected, the output of the primary side control circuit 2, which is dependent on temperature and inversely proportional to the temperature change in the gain of the vibrator 1, is quantized, and an offset value that reduces an error in the sensor output due to temperature change is added to the quantized output of the primary side control circuit 2 in the secondary side control circuit 3, thereby correcting the sensor output. This allows the sensor output to be corrected simply by adding an offset value that reduces an error in the sensor output due to temperature change to the secondary side control circuit 3, so that the configuration of the vibration type angular velocity sensor 101 can be simplified, unlike the case where an offset value other than an offset value based on the output of the primary side control circuit 2, which is dependent on temperature, is added.

[0074] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the description of the embodiments above, and further includes all modifications within the meaning and scope of the claims.

[0075] For example, in the first and second embodiments, an example was shown in which a ring-shaped vibrator was used, but the present invention is not limited to this. For example, as long as the vibrator has a symmetrical shape, a disk-shaped, cup-shaped (wine glass-shaped), octagonal-shaped vibrator, etc. may be used.

[0076] In the above first and second embodiments, an example was shown in which a closed control loop was formed by a vibrator, an amplifier circuit, a synchronous detection circuit, a loop filter, a modulation circuit, and a drive circuit, but the present invention is not limited to this. For example, the control loop may be formed by a configuration other than the configuration including the amplifier circuit, the synchronous detection circuit, the loop filter, the modulation circuit, and the drive circuit.

[0077] Furthermore, in the above first and second embodiments, an example has been shown in which an integral filter is used as a loop filter, but for example, a loop filter other than an integral filter may also be used.

[0078] In the above first embodiment, an example is shown in which the first offset value before switching is a1+b1 and the second offset value is a2+b2, and the first offset value after switching is -a1+b1 and the second offset value is -a2+b2, but the present invention is not limited to this. For example, the first offset value before switching may be a1 and the second offset value a2, the first offset value after switching may be -a1, which is the first offset value a1 before switching with its polarity inverted, and the second offset value after switching may be -a2, which is the second offset value a2 before switching with its polarity inverted. As a result, although some residual temperature fluctuation components of the bias remain before and after switching between electrode 50 that induces primary vibration in the vibrator by primary side control circuit 2 and electrode 50 that detects secondary vibration of the vibrator by secondary side control circuit 3, the first offset value for making a correction inversely proportional to the square of the gain of vibrator 1 and the second offset value for making a correction inversely proportional to the first power of the gain of vibrator 1 are symmetrical with respect to zero (a predetermined reference value), so that it is possible to suppress the loss of symmetry in the control of the vibration type angular velocity sensor before and after switching.

[0079] In the above first embodiment, the first offset value before switching is a1+b1 and the second offset value is a2+b2, and the first offset value after switching is -a1+b1 and the second offset value is -a2+b2. However, the present invention is not limited to this. For example, the median may be determined so as to cancel the first term of the above formula 3 (i.e., the first offset value is fixed at b1), and the second offset value before switching is a2+b2 and the second offset value after switching is -a2+b2. That is, only the second offset value may be a value that is symmetrical with respect to a predetermined reference value before and after switching.

[0080] In the above first and second embodiments, the provisional first offset value a1 and the provisional second offset value a2 before and after the switching are determined so that the residual of the bias component is minimized before and after the switching, but the present invention is not limited to this. For example, the first offset value and the second offset value before and after the switching may be determined so that they are close to the values ​​at which the residual of the bias component is minimized before and after the switching.

[0081] In the above first embodiment, the addition / subtraction amount adjustment circuits 4a and 4b and the addition / subtraction amount adjustment circuits 5a and 5b (four individual circuits) are provided to output the offset value a+b and the offset value -a+b, but the present invention is not limited to this. In the present invention, it is sufficient to provide a circuit that outputs signals corresponding to the offset value a+b and the offset value -a+b. [Explanation of symbols]

[0082] 1 Transducer 2 Primary side control circuit 3 Secondary side control circuit 34 Loop Filter 41 Switch (1st switch) 42 Switch (second switch) 43 Switch (3rd switch) 44 Switch (4th Switch) 50 electrodes 100, 101 Vibration type angular velocity sensor

Claims

1. A vibrator and a primary side control circuit having a closed control loop, the output of which induces a primary vibration in the vibrator; a secondary-side control circuit having a closed control loop that detects secondary vibrations generated in the vibrator due to an angular velocity applied to the vibrator, and configured to correct a sensor output by adding an offset value to the closed control loop; The primary side control circuit is configured to be able to switch electrodes that induce the primary vibration in the vibrator, The secondary-side control circuit is configured to be able to switch electrodes for detecting the secondary vibration of the vibrator, The vibration-type angular velocity sensor, wherein the offset value after switching and the offset value before switching are symmetrical with respect to a predetermined reference value.

2. the secondary-side control circuit includes a loop filter within the closed control loop; 2. The vibrating angular velocity sensor according to claim 1, wherein the sensor output is corrected by adding the offset value to an input of the loop filter.

3. 2. The vibration type angular velocity sensor according to claim 1, wherein, when the offset value before switching is a, the offset value after switching is −a, which is the inverse of the polarity of the offset value before switching.

4. The temporary offset value before switching is set to a, The temporary offset value after switching is set to −a, When the provisional offset value for the median value between the sensor output before switching and the sensor output after switching is b, 2. The vibration-type angular velocity sensor according to claim 1, wherein the offset value before switching is a+b, and the offset value after switching is −a+b.

5. 2. The vibration type angular velocity sensor according to claim 1, wherein, when the sensor output is corrected in an analog manner, a first offset value based on the output of the primary side control circuit, which is inversely proportional to the temperature change of the gain of the vibrator, and a second offset value based on a constant signal independent of temperature are added to a closed control loop of the secondary side control circuit to correct the sensor output from the secondary side control circuit, which is inversely proportional to the square of the temperature change of the gain of the vibrator, and the sensor output is corrected by adjusting the amounts of the first offset value and the second offset value added.

6. The temperature-dependent gain of the oscillator is G Ｒ (T), and A, B, and C are constant values ​​that do not depend on temperature. The sum of the error in the sensor output that occurs in the closed control loop of the secondary control circuit due to an error signal generated from a circuit block that constitutes the secondary control circuit and the error in the sensor output that occurs in the closed control loop of the secondary control circuit due to crosstalk from the primary control circuit to the secondary control circuit is V. Ｏｕｔ＿Ｔｏｔａｌ＿Ｅｒｒｏｒ is expressed by the following formula, and the first term of the formula, A / G Ｒ ２ The amount of addition of the first offset value based on the output of the primary side control circuit, which is dependent on temperature and inversely proportional to the temperature change of the gain of the vibrator, is adjusted so as to reduce B / G Ｒ 6. The vibration-type angular velocity sensor according to claim 5, wherein the sensor output is corrected in an analog manner by adjusting the amount of addition of the second offset value based on the constant signal independent of temperature so as to reduce (T). [Equation 1]

7. 2. The vibration type angular velocity sensor according to claim 1, wherein when the sensor output is digitally corrected, the output of the primary side control circuit, which is dependent on temperature and inversely proportional to the temperature change of the gain of the vibrator, is quantized, and the offset value that reduces an error in the sensor output due to temperature change is added to the quantized output of the primary side control circuit by the secondary side control circuit, thereby correcting the sensor output.

8. The vibrating angular velocity sensor according to claim 1 , wherein the vibrator includes a ring-shaped vibrator.

9. the primary-side control circuit includes a first switch provided on an input side of a signal to the vibrator, and a second switch provided on an output side of a signal from the vibrator, the secondary-side control circuit includes a third switch provided on an input side of a signal to the vibrator, and a fourth switch provided on an output side of a signal from the vibrator, When the first switch and the second switch are switched, the primary side control circuit switches the electrodes that induce the primary vibration in the vibrator, 2. The vibration type angular velocity sensor according to claim 1, wherein the electrodes for detecting the secondary vibration of the vibrator are switched by the secondary side control circuit by switching the third switch and the fourth switch.

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